Manifold for a liquid cooling system

ABSTRACT

A method including punching a first hole in a parent sheet metal, such that a substantially round section with a first diameter is removed from the hole, forming a second hole by inserting a mandrel into the first hole, causing a portion of the parent sheet metal to deform in a downward direction and increase the diameter of the first hole to a second diameter, the deformed portion of the parent sheet metal is substantially perpendicular to the parent sheet metal, forming a thread into an interior sidewall of the second hole, and forming the parent sheet metal into a water tight manifold.

BACKGROUND

The present invention generally relates to a manifold used in a liquidcooling system, and more particularly to a method of forming a watertight connection to the manifold.

Liquid cooling systems are used to efficiently remove heat fromelectronic components in a computer system, for example amulti-processor computer or server. Such cooling systems may include amanifold and a heat exchanger connected by a series of hoses or pipesand pumps. The heat exchanger may be located at or near variouscomponents of the computer system and the manifold is used to distributea cooling liquid to and from the heat exchanger via the hoses. A seriesof threaded ports may typically be welded to the manifold and accept athreaded fitting, for example a threaded quick connect fitting, used toconnect the hoses to the manifold. The threaded ports are generallymachined components which are then welded or brazed to the manifold.Machining and welding of the threaded ports adds time and cost tomanufacturing of the cooling system, specifically, the manifold.

Quick connect fittings provide the ability to connect and disconnect thehoses from the liquid cooling system with virtually no liquid leakageand without adversely affecting the operation of any liquid remaining inthe cooling system. Further quick connect fittings offer easy andreliable connect and disconnect operations while doing so in a minimumamount of available space without the need for extensive tool operationspace or damaging the associated components of the electronic device,computer or cooling system.

SUMMARY

According to an embodiment of the present invention, a method isprovided. The method may include forming a hole in a sheet metal flatpattern, the hole having a first diameter, forming a hole extrusion inthe sheet metal flat pattern aligned with the hole, the hole extrusioncomprises an inside diameter larger than the first diameter, forming athread in an inner sidewall of the hole extrusion, and forming theparent sheet metal into a water tight manifold.

According to another embodiment, a method is provided. The method mayinclude punching a first hole in a parent sheet metal, such that asubstantially round section with a first diameter is removed from thehole, forming a second hole by inserting a mandrel into the first hole,causing a portion of the parent sheet metal to deform in a downwarddirection and increase the diameter of the first hole to a seconddiameter, the deformed portion of the parent sheet metal issubstantially perpendicular to the parent sheet metal, forming a threadinto an interior sidewall of the second hole, and forming the parentsheet metal into a water tight manifold.

According to another embodiment, a structure is provided. The structuremay include a watertight manifold fabricated from a piece of sheet metaland having a welded seam and a threaded hole extrusion, and a threadedquick connect fitting, the quick connect fitting has an o-ring which isthreaded into the threaded hole extrusion such that the o-ring is indirect contact with a substantially uniform surface of the watertightmanifold.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the invention solely thereto, will best be appreciatedin conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a flat piece of sheet metal according to an exemplaryembodiment;

FIG. 2 illustrates the result of cutting the sheet metal into a flatpattern according to an exemplary embodiment;

FIG. 3 is a cross-section view of FIG. 2, along section line A-A, andillustrates forming a first opening according to an exemplaryembodiment;

FIG. 4 is a cross-section view of FIG. 2, along section line A-A, andillustrates the first opening according to an exemplary embodiment;

FIG. 5 is a cross-section view of FIG. 2, along section line A-A, andillustrates forming a second opening according to an exemplaryembodiment;

FIG. 6 is a cross-section view of FIG. 2, along section line A-A, andillustrates the second opening according to an exemplary embodiment;

FIG. 7 is a cross-section view of FIG. 2, along section line A-A, andillustrates the formation of a thread in the second opening according toan exemplary embodiment;

FIGS. 8, 9 and 10 illustrate folding and welding the flat pattern toform a manifold according to an exemplary embodiment;

FIG. 11 is a cross-section view of FIG. 8, along section line B-B, andillustrates attaching a threaded quick connect fitting to the manifoldaccording to an exemplary embodiment; and

FIG. 12 is a cross-section view of FIG. 11, along section line C-C, andillustrates the quick connect attached to the manifold, according to anexemplary embodiment.

The drawings are not necessarily to scale. The drawings are merelyschematic representations, not intended to portray specific parametersof the invention. The drawings are intended to depict only typicalembodiments of the invention. In the drawings, like numbering representslike elements.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosedherein; however, it can be understood that the disclosed embodiments aremerely illustrative of the claimed structures and methods that may beembodied in various forms. This invention may, however, be embodied inmany different forms and should not be construed as limited to theexemplary embodiments set forth herein. Rather, these exemplaryembodiments are provided so that this disclosure will be thorough andcomplete and will fully convey the scope of this invention to thoseskilled in the art. In the description, details of well-known featuresand techniques may be omitted to avoid unnecessarily obscuring thepresented embodiments.

References in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, andderivatives thereof shall relate to the disclosed structures andmethods, as oriented in the drawing figures. The terms “overlying”,“atop”, “on top”, “positioned on” or “positioned atop” mean that a firstelement, such as a first structure, is present on a second element, suchas a second structure, wherein intervening elements, such as aninterface structure may be present between the first element and thesecond element. The term “direct contact” means that a first element,such as a first structure, and a second element, such as a secondstructure, are connected without any intermediary conducting, insulatingor semiconductor layers at the interface of the two elements.

In the interest of not obscuring the presentation of embodiments of thepresent invention, in the following detailed description, someprocessing steps or operations that are known in the art may have beencombined together for presentation and for illustration purposes and insome instances may have not been described in detail. In otherinstances, some processing steps or operations that are known in the artmay not be described at all. It should be understood that the followingdescription is rather focused on the distinctive features or elements ofvarious embodiments of the present invention.

Manifolds for liquid cooling systems may be designed and fabricated outof sheet metal to meet the design constraints of some customapplications. Traditionally, manifolds are formed and assembled and oneor more threaded ports are subsequently welded on. This method mayintroduce metal shavings into a cavity of the manifold. The metalshavings may become immersed in the liquid cooling system and becomemobile and may impede operation of the pump and degrade cooling of theelectronic components in the computer system. Embodiments, of theproposed invention provide a method of forming a threaded hole extrusionin a sheet metal flat pattern prior to forming the flat pattern into amanifold.

The liquid cooling system must be watertight. Water leaks may result inundesirable damage to the computer system. Traditional threaded portsare costly and time consuming to ensure a water connection. Embodimentsof the proposed invention may reduce the cost and time associated withfabricating the manifold while ensuring a water tight connection.

The present invention generally relates to a manifold used in a liquidcooling system, and more particularly to a method of forming a watertight connection to the manifold. One way to form a water tightconnection to the manifold may include forming a threaded hole extrusionin a sheet metal flat pattern before folding and welding it together toform the manifold. One embodiment by which to form the threaded holeextrusion in the sheet metal flat pattern before folding and welding ittogether to form the manifold is described in detail below by referringto the accompanying drawings in FIGS. 1 to 12.

Referring to FIG. 1, a piece of sheet metal 102 is shown according to anexemplary embodiment. The sheet metal 102 may have a length (l1) and awidth (w1). The sheet metal 102 may be made from any of several knownmetals, including stainless steel, aluminum, brass, steel and copper.Some considerations when selecting a raw material may include corrosionresistance and ductility. Corrosion resistance is important due to theconstant contact with the cooling liquid and ductility plays a role infabricating a threaded hole extrusion. In a preferred embodiment, thesheet metal 102 may be a stainless steel alloy with sufficient corrosiveresistance and adequate ductility to carry out fabrication techniquesdescribed below.

Referring now to FIG. 2, the sheet metal 102 may be formed into a flatpattern 100. The flat pattern 100 may be formed by any known technique,such as, for example, powered shears, manual tin snips, laser cutting,saw cut, corner notched or punch press, among other methods. The flatpattern 100 may have a length (l₂) and a width (w₂). It should be notedthat the length (l2) and the width (w2) of the flat pattern 100 may beless than or equal to the length (l1) and the width (w1) of the sheetmetal 102. The dashed lines may generally indicate fold line where thesheet metal 102 may be bent to form a manifold. The flat pattern 100 mayhave inner dimension which are length (l₃) and a width (w₃). The length(l₃) and the width (w₃) of the flat pattern 100 may be less than orequal to the length (l₂) and the width (w₂) of the sheet metal 102 Thelength (l₃) and the width (w₃) of the flat pattern 100 may directlycorrespond to the dimensions of the finished manifold. Next, one or morethreaded hole extrusions 104 may be fabricated in the flat pattern 100.Fabrication of the threaded hole extrusion 104 will be described indetail below with reference to FIGS. 3-7.

Referring now to FIGS. 3-7, fabrication steps for forming the threadedhole extrusion 104 are shown. Each of FIGS. 3-7 is a cross section viewof FIG. 2, along section line A-A.

In general, a hole extrusion may be designed into a sheet metal part forany number of reasons. The inside diameter of a hole extrusion may serveas a bearing surface, a pivot point or an interface for a press-fit withanother component. Most often, hole extrusions find use as screwattachments, usually cut or formed with threading taps or self-tappingscrews. The threaded hole extrusion 104 of the present embodiment may beused to attached a threaded quick connect fitting used to create awatertight connection between a hose and a manifold in a liquid coolingsystem. The hole extrusion may include a portion of the sheet metalextending in a downward direction substantially perpendicular to a topsurface of the sheet metal. The hole extrusion may also be referred toas a deformed portion of the sheet metal.

Deep-drawn hole-tapping features are often incorrectly referred to asextrusions. Deep-drawn features are produced by gathering apredetermined volume of material into a bubble, then incrementallyreducing the outside diameter while simultaneously increasing the wallheight through multiple redraw stations. Depending on the processdesign, deep-drawn features can have wall thicknesses that are lessthan, equal to or greater than the original sheet metal thickness. Theyalso can achieve greater wall heights than possible with holeextrusions.

First, a hole 106 is punched in the flat pattern 100, as shown in FIGS.3 and 4. The hole 106 will be referred to throughout as the punched hole106. Then an extrusion punch expands the hole to the required insidedimension (ID) forming a hole extrusion 108, as illustrated in FIG. 5.The extrusion height directly relates to a diameter (d₁) of the punchedhole 106, the edge quality of the punched hole 106, the inside diameterof the hole extrusion 108 and the amount of allowable wall thinning.

To approximate the extrusion height, apply the constancy-of-volume rule:“Material volume is neither created nor destroyed by deformation.” Thisis analogous to forming a hamburger—squeezing the patty reduces itsthickness and increases its diameter. The volume of beef doesn't change;the material is merely displaced or rearranged. The same holds true forhole extrusions—as the extruded wall thickness decreases, the extrusionheight increases.

Consider, for example, a hole extrusion designed as a bearing hub in a3.0 mm thick sheet metal part. The design requires an 8.2 mm ID (e.g.(d₂) as shown in FIG. 6) and a minimum wall thickness of 1.5 mm, with aminimum 3.0 mm extrusion height (e.g. (h₁) as shown in FIG. 6). Theconstancy-of-volume rule can be applied as follows to determine if it ispossible to successfully form a hole extrusion with the requireddimensions.

Using the constancy-of-volume rule, calculate the volume of material(V_(M)) available to work with:

V _(M)=[(½A)²−(½B)²]πt

where A is the inside diameter of the hole extrusion; B is the diameterof the punched hole; and t is the material thickness.

Assuming the smallest possible hole diameter that can be punched in theworkpiece is equal to the material thickness:

V _(M)=[(8.2 mm/2)²−(3.0 mm/2)²]π3.0 mm

V_(M)=137.225 mm³

To determine the volume of the extrusion (V_(E)), we treat this as acylinder with open ends and a constant wall thickness:

V _(E)=[(½D)²−(½A)²]πh

where D is the outside diameter of the extrusion and is equal to theinside diameter (A) plus two-times the minimum wall thickness, or 11.2mm. The desired extrusion wall height is 3.0 mm.

V _(E)=[(11.2 mm/2)²−(8.2 mm/2)²]π3.0 mm

V_(E)=137.131 mm³

Therefore, if VM≧VE, there is enough material volume to form theextrusion. In this case, V_(M) slightly exceeds V_(E), so the height ofthe extrusion can be made greater than 3.0 mm, if necessary. Theextrusion height may be controlled by adjusting the diameter (B) of thepunched hole. Thus, if the resulting extrusion height is too high,simply reduce V_(M) by increasing the diameter of the punched hole.

In general, the volume of material available to form a hole extrusionmust be greater than or equal to the volume of material contained withinthe hole extrusion. The amount of material available to produce a holeextrusion of a given diameter and height is proportional to the punchedhole diameter, the diameter of the extrusion and the amount ofpermissible wall thinning. The above parameters are importantconsiderations in order to fabricate the threaded hole extrusion 104.Most importantly, the dimensions of the hole extrusion must besufficient to produce a high quality thread. For purposes of the presentembodiment, a high quality thread is capable of accepting a threadedquick connect fitting at adequate torque to ensure a water tightconnection to the manifold.

With specific reference to FIGS. 3 and 4, the punched hole 106 may beformed in the flat pattern 100 using any known metal fabrication tool,such as, for example a punch press 110. The punch press 110 maygenerally include a top plate 112, a bottom plate 114, and a punch 116.In the present embodiment, the bottom plate 114 may serve as a die whichdirectly corresponds with, and paired to, the punch 116. Duringpunching, the sheet metal 102 may be secured between the top plate 112and the bottom plate 114 while the punch 116 is driven downward throughan entire thickness (t₁) of the sheet metal 102 and into the die orbottom plate 114 and producing a slug 118. Afterwards, the punch 116retracts upward and the sheet metal 102 is released from between the topplate 112 and the bottom plate 114. Alternatively, the punched hole 106may be formed by a piercing technique or a machining technique, amongother processes. Piercing techniques are less than optimal because theyproduce holes with fractures and poor dimensional stability. Fracturesand dimensional variations will affect the quality of subsequentprocessing techniques, such as for example, forming the hole extrusionand threading.

The punched hole 106 may extend through the sheet metal 102 and have avertical sidewall which is essentially perpendicular to a length (l₁)and a width (w₁) of the sheet metal 102. After punching, the punchedhole 106 may be shaved and coined to debur or polish any burs or sharpedges. The punched hole 106 may be circular with a diameter (d₁). Thediameter (d₁) of the punched hole 106 may depend on the materialthickness, the volume of material available, and the desired holeextrusion size.

Once the correct volume of material has been established, the quality ofthe punched hole 106 becomes a prime concern. All hole extrusions startas hole expansions, where a punch is forced into a blanked hole, causinga circumferential elongation or stretching of the cut edge. Absolutevalues of expansion limits depend on the material, tool design,lubrication and edge quality of the punched hole. Circumferentialelongation and quality of the hole extrusion may be improved byimproving the edge quality of the punched hole 106. The edge quality ofthe punched hole 106 may be improved by improving the quality of theoriginal cutting operation, using a high quality cutting operation, orusing a shaved cut and deburred break edge operation.

Reducing punch-to-die cutting clearance can improve the edge quality ofthe punched hole 106. This results in a larger shear (cut) band, acorrespondingly smaller fracture zone and small burrs forming on thebackside of the hole. A larger shear band also produces a largercold-worked zone that, combined with the small burrs, may still limitmaximum edge stretchability.

Another option for improving hole quality is to use a step punch. Thefirst point diameter cuts an initial hole while the second pointdiameter re-cuts the hole to provide a higher-quality cut and a moreprecise diameter.

Many of the problems associated with step punches result from theelastic behavior of the material being punched. When punching holesusing conventional punch-to-die clearance (approx. 5 to 8 percent perside), the punching stress may force the hole-edge periphery outward incompression. When the slug breaks free, the compressive stresses relaxand the punched hole relaxes inward toward the punch point.

The opposite occurs when applying engineered cutting clearances (approx.9 to 20 percent per side). In this case, the punching stress pulls thematerial around the punch hole-edge periphery inward in tension. Thehole relaxes outward from the punch point when the slug breaks free.

Because the hole often changes shape during the second cutting step,problems such as chipping, wear, galling or adhesion arise in as littleas a few hundred or a few thousand cycles. These conditions ultimatelydegrade the edge quality of the hole and its ability to deform into thedesired hole extrusion.

After the hole has been shaved, a small radius may be coined, forexample about 0.010 in to about 0.020 in, on the bottom side to compressany burrs that may serve as stress risers. Now that the hole is properlyprepared, it may then be extruded as described below with specificreference to FIGS. 5 and 6.

With specific reference to FIGS. 5 and 6, the punched hole 106 may beextruded to form the hole extrusion 108. More specifically, the holeextrusion 108 may be formed by inserting an extrusion punch into thepunched hole 106 and cause a portion of the sheet metal 102 to deform ina downward direction. The hole extrusion 108 may extend in a directionperpendicular to the sheet metal 102 with a height (h₁), measured from abottom surface of the sheet metal 102 to a bottom surface of the holeextrusion 108. A second height (h₂), measured form a top surface of thesheet metal 102 down to the bottom surface of the hole extrusion 108 isequal to the thickness (t₁) of the sheet metal 102 plus the height (h₁)of the hole extrusion 108. The hole extrusion 108 has a wall thickness(t₂) which, in most instances will be equal to or less than thethickness (t₁) of the sheet metal 102. The hole extrusion 108 may alsobe circular with an inside diameter (d₂). The height (h₁) of the holeextrusion 108 may depend on any or all of the diameter (d₁) of thepunched hole 106, the inside diameter (d₂) of the hole extrusion 108,the thickness (t₁) of the sheet metal 102, the wall thickness (t₂) ofthe hole extrusion 108, in consideration with the ductility of the alloyused as the sheet metal 102.

In an embodiment, the hole may be extruded in the direction opposite ofpunching. This may subject the sheared edge to the most deformation andmay be advantageous because the sheared edge, or leading edge, will haveless damage as a result of the punching technique as compared to thefracture zone, or trailing edge.

The hole extrusion 108 may be formed in the flat pattern 100 using anyknown metal fabrication tool, such as, for example a punch press 120.The punch press 120 may generally include a top plate 122, a bottomplate 124, an extrusion punch 126, and a knockout pin 128. The top plate122 may alternatively be referred to as a stripper plate and the bottomplate 124 may alternatively be referred to as a die or a bushing.

The extrusion punch 126 may preferably be fitted with a locating feature130, also known as a pilot point. The locating feature 130 is used tolocate or align the flat pattern 100, and more specifically the punchedhole 106, in the punch press 120. In general, the locating feature 130will be equal in size, or slightly smaller, and have a similar shape asthe punched hole 106. If the locating feature 130 is either too big ortoo small the punched hole 106 may not properly located in the punchpress 120 causing misalignment between the punched hole 106 and the holeextrusion 108. A leading edge or nose of the extrusion punch 126 willpreferably be radiused (a) and perfectly aligned with the straightsection of the bottom plate 124. Both areas must be highly polished,preferably along the working direction of the punch, as this portion ofthe extrusion punch 126 is subjected to extreme heat and pressure. Underthese conditions, a very small scratch, unperceivable to the naked eye,will quickly lead to galling in just a few press strokes.

In an embodiment, to reduce wear during punch extraction, a back relief(b) may be provided behind the straight section of the extrusion punch126. This allows lubrication to reach behind the punch to lubricate thetool surface when the punch extracts. It should be noted that the backrelief (b) in the figure is exaggerated for purposes of clarity. Aslittle as 0.001 in to 0.002 in per side can provide great benefits. Itmay be beneficial to plumb an oil line in the die to apply lubricationat this point.

An inner wall of the bottom plate 124 may preferably be tapered (c) tofacilitate easy removal of the work piece, the sheet metal 102, from thepunch press 120. For example, at least 1 degree of taper may besufficient; however, the taper may be increased if the tolerance for theoutside dimension of the hole extrusion 108 allows. The knockout pin 128is provided inside the bottom plate 124 to help lift the workpiece, thesheet metal 102, from the bottom plate 124. The knockout pin 128 is usedto prevent misfeeds in automated punch press processes. In addition, anupper edge of the bottom plate 124 may also be radiused (d) tofacilitate easy removal of the workpiece and to prevent the formation ofa stress concentration and associated cracking or fracturing.

Alternate techniques, such as, a pierce extrusion technique may be lessthan optimal because they produce hole extrusions with fractures anddimensional stability is very unpredictable. Fractures and dimensionalvariation will affect the thread quality in the final threaded holeextrusion 108.

It should be noted that the punch press 120 may include manuallyoperated presses with tooling for a single hole extrusion per cycle oran automated production size punch press with tooling for multiple holeextrusions per cycle. In an embodiment, the punch press 120 will havetooling capable to form all the required hole extrusions of a singleflat pattern in one cycle. In another embodiment, the tooling of thepunch press 110 used to fabricate the punched hole 106 and the toolingof the punch press 120 used to fabricated the hole extrusion 108 may becombined in a single punch press to fabricated both the punched hole 106and the hole extrusion 108 in one cycle.

With specific reference to FIG. 7, a cross-section view of the threadedhole extrusion 104 is shown after a threading operation is performed.More specifically, a female thread 132 is cut or formed from an innersidewall of the hole extrusion 108 (FIG. 6). In a preferred embodiment,the female thread 132 is cut using a cut tap. The thread size willcorrespond to a threaded quick connect fitting having matching malethreads. In general, the inside diameter (d₂) of the hole extrusion 108should be about equal to a diameter of a tap drill of the desired threadsize to ensure proper formation of the threads. Additionally, the wallthickness (t₂) of the hole extrusion 108 (FIG. 6) must be sufficientlythick to ensure a high quality thread having adequate strength isformed. A female thread 132 with adequate strength is one which willsupport tightening of the threaded quick connect fitting to a requiredtorque to form a water tight seal. In an embodiment, the threaded quickconnect fitting may be fitted with an o-ring and the required torquewould be any torque sufficient to adequately compress the o-ring toensure a water tight seal.

In an embodiment, the inside diameter (d₂) is determined to ensure aseventy percent thread engagement between the female thread 132 and themale thread of a threaded quick connect fitting. The extrusion height(d₁) may determine the number of female threads 132 in the threaded holeextrusion 104.

The first thickness (t₁) may range from about 1 mm to about 3 mm, andranges between. In some embodiments, the diameter (d₁) of the punchedhole 106 may range from about 1 mm to about 3 mm, and ranges between. Ina preferred embodiment, the second diameter (d₂) may be 19 mm.

In an embodiment, the inside diameter (d₂) of the hole extrusion 108 isapproximately twice the first diameter (d₁). In a preferred embodiment,the inside diameter (d₂) of the hole extrusion 108 is approximately aminimum of four times a height of the hole extrusion 108 (h₁). In anembodiment a height (h₁) of the hole extrusion 108 is at least threetimes a pitch of the thread. In a preferred embodiment, the secondthickness (t₂) of the hole extrusion 108 is at least two times adifference between a major diameter of the thread and a minor diameterof the female thread 132.

Referring now to FIGS. 8, 9 and 10, the sheet metal 102 may be folded orbent to form a manifold 134 and a threaded quick connect fitting 136 maybe installing in the threaded hole extrusion 104. FIG. 9 is a frontsection view of FIG. 8, and FIG. 10 is a side section view of FIG. 9.

In general, the flat pattern 100 is bent along the dashed lines shown inFIG. 2 and joined along all open edges. The joining may be done bywelding, soldering or brazing to form a water tight vessel or tank. Itshould be noted that at this stage of fabrication what will become aninner surface of the manifold 134 will have already been deburred andcleaned, leaving it substantially free of any fabrication contaminants,for example metal shavings, that may damage the cooling system whenplaced in service. The hole extrusion 108 may have been subject todeburring, shaving and coining, to remove any burs and sharp edges.

Next, the threaded quick connect fitting 136 may be installing in thethreaded hole extrusion 104, as shown in FIGS. 11 and 12. FIG. 11 is across section view of FIG. 8 along section line B-B. FIG. 12 is ansection view of FIG. 11 section C illustrating a detailed view of thethreaded quick connect fitting 136 installed in the threaded holeextrusion 104. While only four threaded quick connect fittings 136 areshown as installed on one side of the manifold 134, any number ofthreaded quick connect fittings 136 may be installed on any side(s) ofthe manifold 134 based on various design requirements and constraints.Similarly, the threaded hole extrusion 104 may be fabricated anywhereand on any side of the manifold 134. As mentioned above, in anembodiment, the threaded quick connect fitting 136 will be fitted withan o-ring 138. It should be noted that the tightening torque of thethreaded quick connect fitting 136 should not depend on the thread size,rather the tightening torque should be sufficient to adequately compressthe o-ring 138 to ensure a water tight seal.

The threaded quick connect fitting 136 may be made from any of severalknown metal materials, including stainless steel, aluminum, brass, steeland copper. The threaded quick connect fitting 136 may have one or morecomponents. In an embodiment, the threaded quick connect fitting 136 mayhave male threads, a hexagon top, a cavity 140 for which the coolingliquid will pass through. The o-ring 138 may be positioned in a groovein an underside of a head of the threaded quick connect fitting 136. Asmentioned above, the o-ring 138 is used between the threaded quickconnect fitting 136 and the manifold 134 to ensure a water tight seal.

Consider, for example, a hole extrusion designed as a bearing hub in a3.0 mm thick sheet metal part. The design requires an 8.2 mm ID and aminimum wall thickness of 1.5 mm, with a minimum 3.0 mm extrusion height(e.g. h₁). The constancy-of-volume rule can be applied as follows todetermine if it is possible to successfully form a hole extrusion withthe required dimensions.

In an embodiment of the present invention the threaded hole extrusion104 will be designed to accept or receive an 18 mm threaded quickconnect fitting 136. An 18 mm threaded quick connect fitting 136 mayhave an M18×1.5 male thread with a minor diameter of about 16.3 mm,major diameter of about 17.2 mm, and a tap drill size of about 16.5 mm.If in the present embodiment, the material thickness of the sheet metal102 is about 3 mm, the threaded hole extrusion 104 requiresapproximately a 16.5 mm ID and a minimum wall thickness of about 1.5 mm,with a minimum 3.0 mm extrusion wall height (e.g. H₁). It should benoted that the minimum wall thickness and the minimum extrusion heightare dependent on the thread size and the desired thread engagement. Theconstancy-of-volume rule can be applied as follows to determine theconstraints or limitations of forming the above threaded hole extrusion104.

Assuming the smallest possible hole diameter that can be punched in thework piece is equal to the material thickness, the constancy-of-volumerule may be used to calculate the volume of material (V_(M)) available:

V _(M)=[(17 mm/2)²−(7.0 mm/2)²]π3.0 mm

(t ₂)=565.2 mm³

To determine the volume of the extrusion (V_(E)), we treat this as acylinder with open ends and a constant wall thickness:

V _(E)=[(½D)²−(½A)²]πh

where D is the outside diameter of the extrusion and is equal to theinside diameter (A) plus two-times the minimum wall thickness, or 11.2mm. The desired extrusion wall height is 3.0 mm.

V _(E)=[(23/2)²−(17/2)²]π3.0

V_(E)=565.2 mm³

Therefore, if V_(M)≧V_(E), there is enough material volume to form theextrusion. In this case, V_(M) slightly exceeds V_(E), so the height ofthe extrusion can be made greater than 3.0 mm, if necessary. Theextrusion height may be controlled by adjusting the diameter (B) of thepunched hole. Thus, if the resulting extrusion height is too high,simply reduce V_(M) by increasing the diameter of the punched hole.

In the present embodiment, a method of forming a female thread in a holeextrusion of a sheet metal, forming the sheet metal into a manifold andthen joining a quick connect in the manifold provides a water tightconnection which may be free of metal shavings and more economical toproduce than traditional methods.

The invention described above provides a water tight manifold. Thecavity of the manifold may be free of metal shavings and may be formedprior to joining with the threaded quick connect fitting 136. Theresulting manifold may be water tight. The invention described above mayform a threaded extrusion able to receive a quick connect to insurewater tightness for a cooling system.

It may be noted that not all advantages of the present invention areincluded above.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

1-16. (canceled)
 17. A structure comprising: a watertight manifold fabricated from a piece of sheet metal and having a welded seam and a threaded hole extrusion; and a threaded quick connect fitting, the quick connect fitting has an o-ring which is threaded into the threaded hole extrusion such that the o-ring is in direct contact with a substantially uniform surface of the watertight manifold.
 18. The method of claim 17, wherein an inside diameter of the threaded hole extrusion is approximately a minimum of four times a height of the threaded hole extrusion.
 19. The method of claim 17, wherein a height of the threaded hole extrusion is at least three times a pitch of the thread.
 20. The method of claim 17, wherein a wall thickness of the threaded hole extrusion is at least two times a difference between a major diameter of the thread and a minor diameter of the thread. 